One of the biggest public inquiries in British legal history is to open later on Monday into allegations of abuse in 13 care homes and orphanages in Northern Ireland.

The historical institutional abuse inquiry will examine claims of sexual and physical abuse including at the Kincora boys' home in east Belfast, at which a senior Orangeman and a number of loyalist extremists raped children.

The inquiry may also explore allegations that the security forces, both MI5 and RUC special branch, knew about the abuse in Kincora but failed to act against those responsible because many of the abusers were state agents.

Chaired by the retired judge Sir Anthony Hart QC, the inquiry, based in Banbridge courthouse, will hear written and oral testimony from 434 individuals and their stories of abuse in institutions, which range from young offenders centres to orphanages run by Catholic nuns.

It will also investigate how 120 children from these institutions between 1947 and 1956 were sent to Australia as part of a child migration policy at the time.

The hearings will last until June 2015 and could cost up to £19m.

Most of the applications (280) have come from individuals residing in Northern Ireland. However, there have also been 61 from Australia, 63 from Great Britain, 20 from the Republic of Ireland and eight from other countries.

Up to 300 people are expected to turn up in person to give evidence to the inquiry, which was established by the Northern Ireland assembly following a long campaign by victims of abuse in institutions.

A victims' support service has been established through the Office of the First Minister and Deputy First Minister of Northern Ireland to provide support and advice to victims and survivors before, during and after the inquiry.